Creasing Rule Selection for Coated Folding Boxboard Conversion
Selecting steel creasing rules and matrix channels for coated FBB requires matching board caliper and CTMP core shear limits to prevent surface cracking.
Female Counter Die
Creasing Tool
Recessed channels mounted on the anvil of a die-cutting press receive scoring rules to form permanent score lines in paperboard blanks. A bottom tooling impression sheet or creasing plate functions as a female counter die during high-speed converting. Steel creasing rules push paperboard down into matching channels, forcing internal fiber layers to yield under combined shear and compression forces.
Channel dimensions control crease depth and width, dictating the ultimate folding force of converted carton blanks. Materials used for lower tooling include phenolic grooves and self-adhesive plastic matrix strips. The tooling component operates strictly within flatbed and rotary die-cutting systems, terminating application where score lines are formed by male-to-male embossing rolls.
Channel Geometry
Channel width calculation follows established converting formulas incorporating board caliper and creasing rule thickness. Recommended channel width equals one rule thickness plus one point five times board caliper for folding boxboard. Channel depth correlates directly with sheet thickness, ensuring sufficient penetration without rupturing lower linerboards.
Matrix Alignment
Precise centering of scoring rules over channel centers prevents asymmetrical crease formation along score lines. Offset positioning causes unequal fiber displacement, generating uneven fold resistance on opposite carton panels. Press operators verify registry using carbon impression sheets or electronic registration cameras prior to initiating high-speed production runs.
Misaligned counter channels produce cracked outer liners or uneven carton squareness during high-speed gluing operations.